#include <cstdio>
#include <algorithm>
#include <queue>
#include <cstdlib>
#include <cstring>
using namespace std;
const int INF=0x3f3f3f3f;
char mp[15][15];
bool vis[15][15];
int ans;
int t,n,m;
struct node{
    int i;
    int j;
    int d;
    node(int _i,int _j,int _d):i(_i),j(_j),d(_d){}
};
bool check(int i,int j){
    if(i<0 || i>=n || j<0 || j>=m || vis[i][j] || mp[i][j]=='.'){
        return false;
    }
    else{
        return true;
    }
}
bool judge(){
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            if(mp[i][j]=='#' && !vis[i][j]){
                return false;
            }
        }
    }
    return true;
}
int bfs(int i,int j,int k,int l){
    queue<node> que;
    que.push(node(i,j,0));
    que.push(node(k,l,0));
    vis[i][j]=vis[k][l]=true;
    int time=0;
    while(!que.empty()){
        node tmp=que.front();
        que.pop();
        int ti=tmp.i;
        int tj=tmp.j;
        int td=tmp.d;
        time=max(time,td);
        if(check(ti+1,tj)){
            que.push(node(ti+1,tj,td+1));
            vis[ti+1][tj]=true;
        }
        if(check(ti-1,tj)){
            que.push(node(ti-1,tj,td+1));
            vis[ti-1][tj]=true;
        }
        if(check(ti,tj+1)){
            que.push(node(ti,tj+1,td+1));
            vis[ti][tj+1]=true;
        }
        if(check(ti,tj-1)){
            que.push(node(ti,tj-1,td+1));
            vis[ti][tj-1]=true;
        }
    }
    if(judge()){
        return time;
    }
    else{
        return INF;
    }
}
int main(void){
    freopen("data.txt","r",stdin);
    scanf("%d",&t);
    int c=1;
    while(t--){
        scanf("%d%d",&n,&m);
        memset(mp,'\0',sizeof(mp));
        memset(vis,false,sizeof(vis));
        for(int i=0;i<n;i++){
            scanf("%s",mp[i]);
        }
        int ans=INF;
        //枚举双起点
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                for(int k=0;k<n;k++){
                    for(int l=0;l<m;l++){
                        if(mp[i][j]=='.' || mp[k][l]=='.'){
                            continue;
                        }
                        memset(vis,false,sizeof(vis));
                        ans=min(ans,bfs(i,j,k,l));
                    }
                }
            }
        }
        if(ans==INF){
            ans=-1;
        }
        printf("Case %d: %d\n",c++,ans);
    }
    return 0;
}
